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tubman · 08-23-2020, 06:15 PM

I'm saying that the heads were designed specifically to have a longer reach because aluminum is not as strong as cast iron and requires more thread length to provide the proper amount of support for the spark plug threads. Chamfering the plug holes reduces the designed thread length and weakens the holding power of the threads in the head. I also believe that thoughtlessly modifying well-engineered designs is not a good idea. I am also saying that anyone that looks to Briggs and Stratton for tips and tricks to upgrade the Ricardo combustion chamber design to improve performance is barking up the wrong tree.

Just about every set of used heads I have ever seen had at least one stripped spark plug hole if not several. Those threads are there for a reason, and I don't think eliminating any is a good idea. Even if enough threads are removed to be visually pleasing , the plug is still shrouded to some degree.

Bottom line is that I don't think it is a good idea, especially when people with the experience and knowledge required to build performance engines have already provided a better alternative.

08-23-2020, 06:15 PM	#34
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,303	Re: AutoLite 216's in Offy heads I'm saying that the heads were designed specifically to have a longer reach because aluminum is not as strong as cast iron and requires more thread length to provide the proper amount of support for the spark plug threads. Chamfering the plug holes reduces the designed thread length and weakens the holding power of the threads in the head. I also believe that thoughtlessly modifying well-engineered designs is not a good idea. I am also saying that anyone that looks to Briggs and Stratton for tips and tricks to upgrade the Ricardo combustion chamber design to improve performance is barking up the wrong tree. Just about every set of used heads I have ever seen had at least one stripped spark plug hole if not several. Those threads are there for a reason, and I don't think eliminating any is a good idea. Even if enough threads are removed to be visually pleasing , the plug is still shrouded to some degree. Bottom line is that I don't think it is a good idea, especially when people with the experience and knowledge required to build performance engines have already provided a better alternative.